How many crash tests does it take to develop the safest car around? Mercedes has an answer

Irish Times

3 days ago

The new
Mercedes-Benz
CLA Shooting Brake is a rather handsome thing. Not everyone will love the 'basking shark' face, with a literally star-studded grille (142 little Mercedes three-pointed stars, all of which light up at night) but it's certainly not ugly.
At the rear, it's positively beautiful, not merely thanks to the smooth, elongated styling but because the CLA Shooting Brake is an estate, and yes, we know that technically shooting brakes should have only three doors, but hey, we're not in charge of picking Mercedes' model names.
How is the CLA Shooting Brake conceptually beautiful? Because, thanks to being an estate, it's a practical, useful car that's not an SUV, and that makes it more beautiful than most.
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SUVs have become an unlovely blight on the motoring firmament (there I go with the stars again … ) so the ability to have a fairly practical 455-litre boot (50 litres up on the four-door CLA), backed up by a 101-litre 'frunk' storage area in the nose means that this low, sleek CLA Shooting Brake can deliver the family-friendly space you need, without the bulk, weight and height that you don't.
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It is, of course, also an all-electric car, at least for now (a hybrid petrol version is on the way too), with an 85kWh battery and a range of up to 761km, which sounds enormous, but then you have to remember that's some 31km shy of the four-door CLA's official range.
Both cars are very, very aerodynamic, but the CLA Shooting Brake sits just 1mm taller than the CLA four-door, and combined with the aerodynamic effect of its standard roof rails, it means that it sacrifices some range. Still, it's enough to theoretically drive from Copenhagen – where Mercedes showed us the car – all the way back to Mercedes HQ in Stuttgart without stopping.
That's thanks to some clever electric tech, including a battery with silicon oxide anodes, which boost energy density by 20 per cent, and a trick air-to-air heat pump that scavenges energy from all over the car – the battery, the brakes, the cabin – to heat things up or cool things down as needed.
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That is, of course, all shared with the four-door CLA, as is the choice of 272hp rear-wheel drive 250+ or 353hp four-wheel drive 350+ models (with the hybrids and a smaller-battery model waiting in the wings).
What's different about the CLA Shooting Brake, its extra storage space aside, is its roof. No, it's not just longer, it also gets a new glass roof that uses electric shading for the first time in a Mercedes.
The new Mercedes Benz CLA Shooting Brake
The CLA Shooting Brake's glass roof uses electric shading that incorporates Mercedes-Benz stars
You can 'open' or 'close' the glass using electrochromic molecules set into the glass, going from fully clear to totally opaque in seven segments.
There's also a little theatre in the glass, as it too is studded with Mercedes-Benz stars which glow gently at night, and allows you – as Mercedes claims – to enjoy a starry night even if it's cloudy.
More importantly, the glass is heat absorbing and soaks up more heat than a conventional sun blind would, which is handy, as headroom in the back seats is tight enough as it is.
The rest is as per the four-door CLA, and you can read about that elsewhere in this paper. However, what really unites the two is safety. Safety has been a Mercedes-Benz obsession for decades. Volvo may have got there first with the three-point seat belt, but Mercedes was the car maker that either invented or popularised the likes of crumple zones, airbags and ABS brakes.
Of course, everyone now has access to incredibly sophisticated electronic safety tech that can watch the road for you, follow the white lines and warn you if you're about to nod off, or about to pull out into the path of another car.
All well and good, but such tech is only useful if the driver actually makes use of it, and according to research carried out in the UK by safety campaigners Brake, 41 per cent of drivers are switching off electronic safety systems because they find their binging and bonging, or their nudges of the steering wheel, far too intrusive.
Dr Christian Glöggler: 'Safety is indispensable, not a compromise'
Dr Christian Glöggler isn't so interested in such technology. As we chat, working our way around a cutaway model of the new Mercedes CLA, it's clear that he is far more excited by the idea of actual, physical occupant protection.
'Safety is indispensable, not a compromise. Safety is, clearly, our DNA,' said Glöggler, who was in charge of the CLA's safety development. 'Here in this model, you can see we have a lot of different metals being used, from high-strength steel to aluminium, and our philosophy is 'the right material at the right place'. This is an efficient, intelligent, engineered body, and our clear focus is to keep the passenger safe, and keep the battery safe.'
This is not the safety of annoying beeps and whistles that distract you when driving. This is the classic Mercedes-Benz safety of actually dealing with the terrifying physics of an actual crash. In this, Glöggler is following in the footsteps of Béla Barényi, the Hungarian-born engineer who actually thought up the idea way back in 1937, but who implemented it first in the Mercedes 190 'Pontoon' of 1952.
'It doesn't matter whether you have a battery or a combustion engine, the idea is the same,' said Glöggler, pointing out the vast steel sections ahead of the passenger compartment, which are largely hidden from view when the car is actually complete. 'It's independent of the drivetrain system, so here at the front, we absorb the energy, and then we can keep the passenger cell very rigid. That was Béla Barényi's idea.'
Peeking under the skin of the CLA shows the incredible structure at work, tucked away and hidden from an owner's view. When you see it, it's more akin to the roll cage of a rally car, wrapping around the car's cabin to deflect, absorb, and reduce any impact. 'Look here, in this B-pillar area' said Glöggler, indicating the central door pillar.
'We have here this hot-formed ultra-high-strength steel. The reason is here we have the passenger, and then you have here, for example, a side impact, another vehicle striking the car from the side, we have here the clear focus to have less deformation in this area and to keep the battery safe.'
Ah, yes: the battery. The Lithium-ion batteries that power modern electric cars have a bit of a reputation for bursting into flames if you smash them and puncture them, and while – statistically – fires in an EV accident are actually very rare, it's clear that Glöggler and his team have thought long and hard about how to keep any potential impact away from the CLA's battery cells.
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'Here you can see where the battery starts,' said Glöggler, pointing at the CLA's interior floor, at about the point where the passenger's heels would be, well back from any potential frontal impact. Then he points out the battery's personalised safety cage, a triangular-shaped section of high-strength steel running around the lower edges of the car's door frames. The section is not solid, but instead packed with a honeycomb-like structure.
'Believe me, this is not only honeycomb,' said Glöggler. 'This is a highly intelligent, optimised structure. We did a lot of optimisation, the angle of the ribs, the thickness of the ribs and also the weight of the ribs. Here, our focus is the side-pole impact test, to absorb the energy with this structure and then behind that, there is no deformation to the battery pack. It's very important to keep the battery safe.'
Glöggler is confident that the CLA will achieve the coveted five-star safety rating from Euro NCAP when it's tested. Indeed, he quietly admits that, well in advance of the results being officially announced, he's had a nod and a wink from the NCAP guys that this is the likely result. However, while NCAP has been highly, possibly rightly, criticised of late for putting too much emphasis on its lab-based tests, and its insistence on fitting the very same electronic safety aids that drivers are turning off in their droves, Glöggler has a different target. Real-world safety.
For all that computers and even AI can rule the roost when it comes to modern safety, the new CLA has been, under Glöggler's supervision, rigorously tested in physical form, including its new central airbag, which pops up between the two front-seat occup-ants to prevent them from clashing heads in a side impact. In any crash, the battery is automatically and immediately isolated, and there are mechanical catches so that the doors, with their electric pop-out handles, can still always be opened from inside or outside, while emergency responders can scan a QR code inside the fuel flap to get instant access to the CLA's full safety info sheet.
'How many crash tests, actual physical crash tests, do you think we did with this car in its development?' Glöggler challenged me. When I answered with a guess of 50, he responded, whip-fast: 'One hundred and 50. And 2,000 full deployments of the airbags.
'And it's also very important for us that our safety is based on real accident data. We started this in 1969, with a unit in the company called Accident Research, and today we still do this, and we also have colleagues in the USA and India, because the traffic is different and the accidents are different. And all of this knowledge is included in the CLA's body.'